virtual-kubelet-stackpath

Virtual Kubelet Provider for StackPath Edge Compute

StackPath's Virtual Kubelet provider allows you to leverage the power of Kubernetes (K8s) to deploy and manage your applications across StackPath's expansive Edge Compute network, increasing scalability and reliability, while decreasing latency.

This feature enables you to use the Kubernetes control plane to create and manage pods as you normally would, without having to worry about managing your own hardware and infrastructure, as StackPath's Virtual Kubelet provider takes care of scheduling these pods for you on our Edge Compute nodes.

Key Features

• Volumes using csi. Mount volumes in your pods using the csi volume type with the driver virtual-kubelet.storage.compute.edgeengine.io.
• Environment variables. Set environment variables for your pods using the Kubernetes env field in your pod specification.
• Instance size selection. Specify resource requirements for your pods using the Kubernetes resources field in your pod specification.
• Startup, liveness and readiness probes. Configure startup, liveness and readiness probes for your pods using - the Kubernetes startupProbe, livenessProbe and readinessProbe fields in your pod specification.
• Private images using image pull secrets. Use Kubernetes image pull secrets to securely pull private container images from a registry using the Kubernetes imagePullSecrets field in your pod specification.
• Run in container. Run commands inside your pods by calling kubectl exec and specifying the pod and command.
• Retrieve logs. Fetch or stream a pod's logs by calling kubectl log [-f] and specifying the pod.

Limitations

• Limited instance types. StackPath Edge Compute product currently supports five instance types: SP-1 through SP-8 (SP// Containers). The provider will launch the smallest instance that provides the resources defined in the pod specification. If the pod specification requires more resources than what is available in the SP-8 instance, the provider will provision the SP-8 instance type. Here are the specifications for each of the available instance types:

  Subscription	Cores	RAM
  SP-1	1	2GB
  SP-2	2	4GB
  SP-3	2	8GB
  SP-4	4	16GB
  SP-5	8	32GB
  SP-6	16	64GB
  SP-7	32	128GB
  SP-8	48	256GB

• Limited network control. The provider currently does not support custom network settings for the StackPath workload. The workload will run with a public and private IP, and network policies must be created separately.

• Limited probe support. The provider currently only supports the httpGet, tcpSocket and exec probe types for startup, liveness and readiness checks. grpc probe type is not currently supported.

• Limited Kubernetes features. The provider only supports some of the Kubernetes pod specification as supported by the StackPath edge compute platform, there may be some advanced features that are not yet supported or that require additional configuration. The provider will ignore any specification that aren't supported when creating the StackPath workload. In addition, the workloads created on the StackPath platform will not have network access to the Kubernetes API or any pods running in nodes that aren't in the virtual kubelet provider.

• Pod name length. The provider is subject to the limitations of StackPath's workload slugs, which are limited to 63 characters. The provider constructs the slug by concatenating the namespace with the pod name separated by a dash. It is important to ensure that this string does not exceed 63 characters, as exceeding this limit will prevent the pod from being created.

Supported PodSpec File Fields

The following is a comprehensive list of supported fields in the PodSpec file when using StackPath's Virtual Kubelet Provider for Edge Compute.

Pod Configuration Fields

• shareProcessNamespace: Allows multiple containers in a pod to share the same process namespace.
• hostAliases: Specifies custom host-to-IP mappings for the pod.
• dnsConfig: Configures DNS settings for the pod.
• securityContext: Defines security-related settings for the containers in the pod, including permissions and access levels.
  • runAsUser: Specifies the user ID that runs the container.
  • runAsGroup: Specifies the primary group ID of the container.
  • runAsNonRoot: Ensures that the container is not run as root.
  • supplementalGroups: Lists additional group IDs applied to the container.
  • sysctls: Configures kernel parameters for the container.
• containers: Specifies the main containers in the pod.
  • name: Specifies the name of the container.
  • image: Specifies the container image.
  • command: Specifies the command to be run in the container.
  • args: Specifies the arguments to be passed to the container command.
  • ports: Configures ports for the container.
  • env: Sets environment variables for the container.
  • resources: Specifies the resource requirements and limits for the container.
  • securityContext (Container-specific):
    • runAsUser: Specifies the user ID that runs the container.
    • runAsGroup: Specifies the primary group ID of the container.
    • runAsNonRoot: Ensures that the container is not run as root.
    • allowPrivilegeEscalation: Allows privilege escalation for the container.
    • capabilities: Specifies Linux capabilities for the container.
  • volumeMounts: Mounts volumes into the container.
  • startupProbe: Configures the startup probe for the container.
  • livenessProbe: Configures the liveness probe for the container.
  • readinessProbe: Configures the readiness probe for the container.
  • lifecycle:
    • postStart: Executed after the container starts.
    • preStop: Executed before the container is terminated due to any reason.
  • imagePullPolicy: Specifies when to pull the container image (only Always and IfNotPresented is supported)
  • workingDir: Sets the working directory inside the container.
  • terminationMessagePath: Specifies the path to the container termination message.
  • terminationMessagePolicy: Specifies how the termination message should be populated.
• initContainers: Defines one or more containers that should run before the main containers in the pod (supports same fields as containers)
• volumes: Configures volumes to be used in the pod.

Getting Started

To use the StackPath Edge Computing Virtual Kubelet provider, you'll need to have the following prerequisites:

• A Kubernetes cluster
• A StackPath account
• Credentials for your StackPath account (a client ID and a client secret)

Installing the Provider

See deployment details

Enabling Remote Management for Pods

To enable remote management for pods, you can use the workload.platform.stackpath.net/remote-management annotation in the pod definition metadata. By setting this annotation to true, the remote management capabilities for the containers listed in the pod will be enabled.

To enable remote management, add the following annotation to your pod definition metadata:

annotations:
  workload.platform.stackpath.net/remote-management: "true"

By default, if this annotation is not provided or set to "false", remote management will be disabled.

For more information about Edge Compute Workload Metadata and other terms related to StackPath Edge Compute, refer to the Learn Edge Compute Terms page.

It is important to note that enabling remote management should be done with caution and only for trusted pods or in controlled environments where appropriate security measures are in place.

Pod Spec File Examples

We've included some sample Pod spec files in the tests/e2e folder to help you get started with. These examples are intended to demonstrate how to configure the virtual kubelet to work with different types of StackPath workloads.

To use one of these examples, simply copy the YAML file and modify it to suit your needs. You can then use kubectl to create the Pod in your Kubernetes cluster.

Note that these examples are provided for demonstration purposes only and may not be suitable for production use. Be sure to review and modify the configuration settings to suit your specific needs.

Conclusion

The Virtual Kubelet Provider for StackPath Edge Compute is a useful tool for deploying Kubernetes pods on StackPath's highly performant and distributed edge infrastructure. With this provider, you can leverage the power of Kubernetes to deploy and manage your applications, while taking advantage of StackPath's Edge Compute capabilities.

While the provider has some limitations, it is a great option for workloads that need to be close to end-users and require low latency or high bandwidth. By seamlessly extending your Kubernetes clusters to the edge with the Virtual Kubelet Provider for StackPath Edge Compute, you can improve the performance and reliability of your applications.

Contributing

If you encounter any issues or have ideas for improvements, don't hesitate to contribute to the project on GitHub. The StackPath team welcomes and values community feedback and contributions.